Apparently the language was popular among early 20th century socialist movements because it was of an international character and therefore not associated with any nationality and its use by international socialist organisations wouldn't show favour to any particular country. It was banned in Nazi Germany and other fascist states because of its association with the left wing, with anti-nationalism, and because its creator was Jewish. It has mostly languished since then but still has around 2 million speakers with about 1,000 native speakers.
2 million out of 8 billion is kind of an issue.
I meant in real life, in ordinary everyday settings. I can also "speak" Morse code with fellow hams on the air, or practice sign language at my local community college, but those are "forced" venues so-to-speak. It's not like I can routinely speak Esperanto every day as a matter of course.
2 million Esperanto speakers is 0.025% of the world's population, which works out as 1 Esperanto speaker every 360,000 square miles where I live. I still haven't met that guy.
It's true that the problem is that it's a diaspora. But that doesn't change the fact that it's quite easy to find Esperanto speakers, and thanks to internet the Esperanto community is actually international. To be an active member of this community builds a better understanding of other points of view, it “internationalizes” your self. As a socialist I think that this is important.
English do that too, but not with the same deepness (I know, English is my second language).
Do you know about the links between Esperantism and socialism?
Stalin, Ho Chi Ming and James Connolly were Esperantists. Hitler threw rocks at it in Mein Kampf.